Avalanche Forecast

Issued: Mar 22nd, 2018 3:35PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs.

swerner, Avalanche Canada

Northwest Coastal.

Storm slabs will likely be reactive to skier and rider triggers. Ridgetop wind will switch from the East to the West potentially forming wind slabs on most aspects. Stick to simple terrain first while gathering observations.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight Thursday: New snow 5-10 cm accompanied by strong easterly winds and freezing level at valley bottom.Friday: Cloudy with possible sunny periods. Ridgetop winds light gusting strong from the northwest. Alpine temperatures near -4 and freezing levels 800 m.Saturday: Mostly cloudy. Snow amounts near 5-10 cm and ridgetop wind strong from the southwest. Alpine temperatures near -4 and freezing levels 500 m.Sunday: Cloudy with snow amounts 5-10 cm. Freezing levels near 1000 m. Ridgetop winds mostly light with strong gusts from the southwest.

Avalanche Summary

On Thursday, a few natural wind slab avalanches were reported up to size 2.5 from steep alpine features on northerly aspects. Wednesday was a similar story showing a natural cycle of wind slab avalanches up to size 2.5 occurred in the alpine.

Snowpack Summary

Up to 10 cm of new snow overlies a variety of buried snow surfaces including pockets of wind slab, a melt-freeze crust on sunny aspects and wet snow down low. On March 9th, surface hoar and/or facets (on sheltered, shady aspects) were buried by the last significant snowfall down 10-25 cm. The new snow will likely have a poor bond to the old snow surfaces.Deeper in the mid-pack, layers of crusts, facets, and isolated surface hoar buried 50 to 100 cm exist from mid- and late-February and a surface hoar/ crust layer from January is buried around 150 to 200 cm. Near the bottom of the snowpack, sugary facets exist in colder and dryer parts of the region, such as the far north.

Problems

Storm Slabs

The recent storm snow will bond poorly to the plethora of old snow surfaces. It will likely step down deeper to the surface hoar layer buried March 9th. Recent strong winds are building reactive wind slabs on most aspects.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Valid until: Mar 23rd, 2018 2:00PM